The proposed Adolescent Medicine Trails Unit (AMTU) at The Children's Hospital of Philadelphia (CHOP) will be one site for the Adolescent Medicine Trails Network for HIV/AIDS Interventions. At the CHOP site, at least 75 HIV-positive and 125 HIV -negative intervention study participants between the ages of 12 to 24 years will be identified and maintained as a potential population for future studies. The Trail Unit staff will be responsible for screening all participates and in the development and maintenance of the central managerial database for the local program. Staff of the CHOP AMTU will contribute to protocol development for the local program. Staff of the CHOP AMTU will contribute to protocol development for the national effort and will complete all data collection efforts required of an AMTU site. The Principle Investigator and Study Coordinator will participate fully in the Network. A central part of the activities of the activities of the AMTU at CHOP will be outreach to HIV-infected youth. Ongoing education, counseling, and testing efforts, as well as the maintenance of an active network of collaborating referral sites, will be critical elements in assuring the availability of the required number of potential research participants. Community education efforts already in existence at CHOP and a strong clinical care program for HIV-infected youth will support the AMTU's ability to be a fully participating site in the national effort. The busy Adolescent Care Center and community adolescent care outreach programs of the Division of Adolescent Medicine at CHOP will be involved in the project as means of identifying appropriate HIV- negative youth for intervention trials. Those coming to the Center will be told about the activities of the Network and their participation will be cultivated while protocols are developed. The Children's Hospital of Philadelphia has a well-developed program to support clinical research efforts and clinical trails like those to be latched by the network. Technical and structural support from the NIH-supported Pediatric General Clinical Research Center, the institutionally-supported clinical trails unit, the pediatric pharmacology research unit, and the Joseph Sakes Research Institute will all be availably to the AMTU at CHOP.